Title Page
요약문
ABSTRACT
Contents
ABBREVIATION USED 13
1. Introduction 22
1.1. Research Background 22
1.2. Thermal Management System for Eco-friendly Vehicle 25
1.2.1. Heat pump system 25
1.2.2. Compact refrigeration system (CRU) 30
1.3. Refrigerant 35
1.4. Compressor 38
1.5. Objective of this thesis and structure 42
2. System design 43
2.1. Compact Refrigeration Unit (CRU) design 43
2.2. Boundary Conditions 45
2.2.1. Cooling capacity (Qc)[이미지참조] 45
2.2.2. Operating temperature of the refrigeration cycle 48
2.2.3. Design conditions of the secondary working fluid 49
2.3. Cycle Analysis 50
2.3.1. Pressure-enthalpy diagram analysis 50
2.3.2. Heat Exchanger Analysis 58
2.3.3. Flow chart of the CRU cycle analysis program 64
2.4. Cycle Analysis Results 66
3. Parts design 72
3.1. Heat Exchanger Selection 72
3.1.1. Evaporator-side flooded heat exchanger 72
3.1.2. Condenser-side plate heat exchanger 76
3.2. Compressor design 80
3.2.1. Compressor types 80
3.2.2. Centrifugal compressor 82
3.2.3. Impeller arrangement of centrifugal compressor 82
3.2.4. Theoretical analysis 87
3.2.5. Impeller shape design 111
3.2.6. Diffuser and Volute 120
3.2.7. Rotor Dynamics 122
3.2.8. Air Bearing 124
3.2.9. Manufacturing 128
4. Experiment results and discussion 133
4.1. Part Evaluation 133
4.1.1. Rotor Natural Frequency 133
4.1.2. Rotor Unbalance 138
4.2. Rotor Dynamics Measurement 140
4.3. CRU system 142
4.3.1. Proto sample of CRU 142
4.3.2. Experiment results 144
4.4. Results and discussion 147
5. Conclusions 149
5.1. Conclusions 149
5.2. Future works 153
REFERENCES 154
OUTCOMES FROM THE RESEARCHES 164
BIOGRAPHY 167
Table 1.1. Thermal properties of refrigerant 37
Table 2.1. Boundary condition of CRU system design 66
Table 2.2. CRU system analysis results for pressure-enthalpy diagram 67
Table 2.3. CRU system analysis results for heat exchanger 70
Table 3.1. Impeller design boundary conditions 110
Table 3.2. Impeller design simulation results 111
Table 3.3. CCD Impeller design boundary conditions 117
Table 3.4. CCD Impeller design results 118
Table 4.1. CRU system performance test result 145
Table 4.2. CRU system performance test result 146
Figure 1.1. Future urban mobility 23
Figure 1.2. Fuel cell bus 24
Figure 1.3. Urban air mobility 24
Figure 1.4. Refrigeration cycle used in the air conditioner 26
Figure 1.5. Air cooler battery thermal management system used in Toyota's Prius 26
Figure 1.6. Chevy Bolt EV battery pack is liquid cooled via a base plate below the cells 26
Figure 1.7. Heat pump system structure and operation for electric vehicle 27
Figure 1.8. Complete improved heat pump system 28
Figure 1.9. Schematic of R134a heat pump 29
Figure 1.10. The compact refrigeration unit 31
Figure 1.11. Denso-manufactured the compact refrigeration unit 32
Figure 1.12. Thermal management system for vehicles equipped with CRU 33
Figure 1.13. Mileage of eco-friendly vehicles equipped with CRU and Eco-driving function 34
Figure 1.14. Refrigerant development timeline 36
Figure 1.15. Compressor types 38
Figure 1.16. Balje diagram 41
Figure 2.1. Compact refrigeration cycle for large scale mobility 43
Figure 2.2. Mini bus air conditioner specification 46
Figure 2.3. Variation of the instantaneous cooling load of the air conditioning with time during the experiment 46
Figure 2.4. Air conditioning system for urban air mobility 47
Figure 2.5. Operating temperature of refrigerant cycle 49
Figure 2.6. Pressure-enthalpy (Mollier) diagram 52
Figure 2.7. Evaporator temperature variation 59
Figure 2.8. Condenser temperature variation 62
Figure 2.9. CRU system parts specification design program flow chart 65
Figure 2.10. Coefficient of performance of CRU cycle by refrigerant 68
Figure 2.11. CRU parts specification by simulation 71
Figure 3.1. Heat exchanger types 74
Figure 3.2. CRU cycle with flooded heat exchanger 75
Figure 3.3. Flooded heat exchanger 76
Figure 3.4. Heat exchanger selection program 77
Figure 3.5. Applicable heat exchanger models 78
Figure 3.6. Over-view size of selected heat exchanger 79
Figure 3.7. Specific speed for CRU compressor 81
Figure 3.8. Centrifugal compressor and name of each part 82
Figure 3.9. Impeller arrangement of centrifugal compressor 83
Figure 3.10. Turbo Compressor pre-evaluation results (Front side air bearing fail) 85
Figure 3.11. Calculation result of centrifugal compressor axial force according to working fluid 86
Figure 3.12. Impeller cross-sectional shapes and names 88
Figure 3.13. The velocity triangle of centrifugal turbo compressor 88
Figure 3.14. Control volume for a generalized turbomachine 92
Figure 3.15. Slip factor in impeller 95
Figure 3.16. Stodola model for slip factor 95
Figure 3.17. Compressor pressure-enthalpy diagram 96
Figure 3.18. Right term of equation 3.50 103
Figure 3.19. Centrifugal compressor design program flow chart 109
Figure 3.20. CCD program input data: Duty and aerodynamic data 112
Figure 3.21. CCD program input data: Gas properties of working fluid 113
Figure 3.22. CCD program input data: Geometry data 114
Figure 3.23. CCD Impeller design options 115
Figure 3.24. CCD program results 116
Figure 3.25. Optimal design parameter 118
Figure 3.26. Optimal shape of the impeller 119
Figure 3.27. Centrifugal compressor diffuser 120
Figure 3.28. Centrifugal compressor volute 121
Figure 3.29. Rotor dynamic modes 122
Figure 3.30. Wheel speed map of rotor 123
Figure 3.31. 1'st generation air foil bearing 124
Figure 3.32. 2'nd generation air foil bearing 125
Figure 3.33. 3'rd generation air foil bearing 125
Figure 3.34. Radial air foil bearing 127
Figure 3.35. Thrust air foil bearing 127
Figure 3.36. Centrifugal compressor for R123 128
Figure 3.37. Section view of centrifugal compressor for R123 129
Figure 3.38. Rotor assembly of centrifugal compressor for R123 129
Figure 3.39. Impeller of centrifugal compressor for R123 130
Figure 3.40. Volute of centrifugal compressor for R123 130
Figure 3.41. Rotor of centrifugal compressor for R123 131
Figure 3.42. Front and rear radial air bearing of centrifugal compressor for R123 131
Figure 3.43. Thrust air foil bearing of centrifugal compressor for R123 132
Figure 3.44. Stator of centrifugal compressor for R123 132
Figure 4.1. Natural frequency of rotor parts by ANSYS simulation 134
Figure 4.2. Natural frequency of each rotor assembly process 135
Figure 4.3. Natural frequency comparison between analysis and measurement of the rotor 136
Figure 4.4. Natural frequency comparison between analysis and measurement of the rotor assembly 137
Figure 4.5. Unbalance measurement results 138
Figure 4.6. Gap sensor in the compressor 140
Figure 4.7. Dynamics measurement results of the rotor (30~110krpm) 141
Figure 4.8. Thrust bearing plate located on one side 141
Figure 4.9. Image of compact refrigeration unit (CRU) 142
Figure 4.10. Image inside of flooded evaporator 143
Figure 4.11. Boiling behavior in a flooded heat exchanger 144